WASHINGTON — Non-Hispanic whites are still by far the largest racial group in the United States, with a population of 197.8 million. (All other racial and ethnic groups make up 37 percent of the population, or 118.3 million.) But Asians, not Hispanics, were the fastest-growing group in 2013.

The country’s Asian population rose by almost 2.9 percent to 19.4 million, an increase of about 554,000. That increase was fueled by immigration, which accounted for 61 percent of the population increase.